Coalpail.com Forum

Pex tubing is rated for 180 at 70 psi. What is a safe temp at 20 psi?

That may be a question best asked of the manufacturer of the PEX you're using.

a better question to ask may be

WHAT IF you I have a temperature overrun and WHAT IF the Pex bursts

WHAT WILL you have then???

Even if you design for normal -- you have to also design for WHAT IF and that may/will eliminate many applications of PEX

The ratings should be printed on the pex itself. It works well for ng oil or other sources of ondemand heat. But I have been hesitant to use it in a coal/wood system. A temp/pressure relief is helpful with a source of fresh water. A tempering valve is helpful, etc.

But as mentioned above, whathappens ifyouhave a water line failure, the valve sticks, your circulator pump fails, etc?

A boiler can usuallymsurvive a lot of heat, but the pex gets soft as temps rise towards max.

After all, you don't want to be in a situation where youhave to dump the warp core...or emergency cool off to prevent majorhome damage by sacrificing your boiler.

That being said, I've read some who use pex for the last section of line, with everythingnnear the boiler being copper or iron.

Everything is a risk, even coal burning itself. PEX sure is nice with crimpers. I installed a ng boiler system for my fil and it works wonderfully, but I keep telling myself NOT to use it in my baseboard/radiator system (currently offline during a majormremodel, using forced air hand fired), even though it would be easier and faster in some places.

In floor is muc more common for PEX usage, which uses cooler temps, 140-170 typically.

Hope this helps. Sorry for typos, Android systems don't believe users need arrow keys

I asked pexsupply.com customer service and they said 200 hundred degrees is the max temp. Does not matter that the pressure is lower. As for not using pex, I used up 600 feet of tubing. can't imagine paying for copper! I have the boiler coming on at 150 and it drifts up to around 175. There are 2 dump zones that are set at around 180.Been firing since Sept. 17th with no problems so far(knock on wood).

Sister inlaw home is 100% plumb with pexs piping that's being heated with a central wood boiler. Hasn't had a issue yet with pexs

Still not sold on that stuff. Copper's tried and true for over 100 years. Expensive, yes - but it works. Keep the plastic where it belongs - wrapped around a baloney sandwich.

Wiz wrote:Sister inlaw home is 100% plumb with pexs piping that's being heated with a central wood boiler. Hasn't had a issue yet with pexs

Thank You!

I think I'll be happy with mine if I ever get it online that is..

I like the fact it bends..

Just what in the hell is that there device Grumpy?? You building a nuke reactor? Looks damn purty!

SMITTY wrote:Just what in the hell is that there device Grumpy?? You building a nuke reactor? Looks damn purty!

Just a manifold, I would have used two single units knowing what I know now, but its in so I'll live with it.. BTW I would never go back to copper after doing this install.

Interesting. Last person I talked to that used it said it was a nightmare to work with - kept coiling up like a rattlesnake. Had to feed it 120°+ water to get it to conform. Maybe there's different grades of that stuff?? Who knows ...

Good to know.

SMITTY wrote:Still not sold on that stuff. Copper's tried and true for over 100 years. Expensive, yes - but it works. Keep the plastic where it belongs - wrapped around a baloney sandwich.

I got hard water that eats copper like coal ash eats SS. I plumb house with 80 % pex last year when installing ka6, zone 1 is still copper.

Wow that sucks ... could definitely see that happening. Wonder how they dealt with that in the old days? Must've kept a stockpile of copper out in the shed ...